Deal With the Devil
by Face of Poe
Summary: ** spoilers for s3e3 His Last Vow ** Mycroft visits Sherlock after his arrest; Sherlock does some deducing about Mary, Magnussen, and motives. Short one-shot drabble-ish fic.


**A/N**: Something of a companion piece with **How Would You Know? **and **Rarely So Lazy**, season three inspired short fics featuring Sherlock and Mycroft.

This one is pretty much self-indulgent speculation about some of the coincidences of the season. ;-)

**Deal With the Devil**

Sherlock was sitting so still, hands folded in front of him and resting on the table, eyes closed, he barely seemed to register Mycroft's arrival in the small holding room. The moment the door shut behind the stiff older brother, however, pale eyes opened and darted immediately to the camera in the corner of the room; the red light blinked off.

Unclasping his hands, Sherlock pulled them back into his lap. He sat back, gaze shifting down to the chair opposite him, a silent but commanding invitation for his brother to join him at the table. Laying his umbrella down on the smooth metal surface, Mycroft obliged and met the intent gaze steadily.

"I tried to come sooner; Mummy is beside herself."

"How does it feel?"

He blinked. "What? Knowing my brother is a murderer?"

"Knowing your brother is an _idiot_," Sherlock hissed, eyes narrowing to slits. Mycroft pursed his lips and waited. "You've been clever, far cleverer than I ever gave you credit for. Plotting and scheming your cold heart out in preparation for my return last year." A light sneer touched the corner of his lips. "The one thing I couldn't work out in all of this, the obvious question: knowing Magnussen had discovered her- why would Mary not simply leave England, start anew someplace else?"

"For ordinary people, Sherlock, love can be a powerful motivator indeed."

He shook his head though, a genuine smile emerging beneath his stoic exterior. "No; not her. Not Mary. Sure, she loved John a great deal, but once she'd worked out what happened last November, who was behind the attack, she would have left for his safety as much as her own except… she knew she was safe in England, didn't she? She'd already played her hand long before. Made her deal."

"With Magnussen?"

Sherlock stood quickly, the metal legs of the chair scraping against the concrete floor as it flew backwards and toppled. "Oh, brother mine," he hissed, "do cease playing games. When did you meet her?"

A long-suffering sigh escaped him before he shrugged lightly and answered the question honestly. "About three years back. Shortly before you went on your extended holiday. CIA was after her, as you can well imagine."

"And once you'd exhausted her for information, you saw a better use than giving the CIA your scraps and extraditing her. Leaving John in the dark, that was your idea- but you knew he'd need looking after once I was gone. So you came up with a plan, insinuated her into his surgery. Make sure he didn't do anything stupid, let you know if he began to toy with the fantasies floating around the internet of my faked suicide and putting himself at risk."

Mycroft smiled thinly, observing his younger brother closely. Sherlock still stood, chair forgotten on the floor, but the ire was gone from his eyes, expression unfocused as he worked through the puzzle. "Their _romantic_ connection," Mycroft sniffed at the word, "was not part of the plan. If it makes you feel any better."

Sherlock let out a derisive breath and turned abruptly to retrieve the uncomfortable seat, setting it back down with a loud bang and throwing himself into it. "Worked out all the better for you though, didn't it? You used to be so clumsy, offering money to the likes of John Watson to spy on me- and then you could see ahead to when you could extend her usefulness upon my return. Your very own CIA-trained intelligence agent to keep you apprised of my doings, in exchange for your promises of protection from her former employer. And several other agents undoubtedly interested in her whereabouts," he added as an afterthought. "And then Magnussen came into the picture.

"He had something on Mary, something you couldn't protect her from. Sure, you could keep her out of prison, but if he'd informed the right people of her identity and whereabouts… and that's why you wanted me to stay away from him. He wasn't under your _protection_; you'd already set the hit, probably began planning it shortly after Lady Smallwood visited me. Your threat towards Anderson- expecting Magnussen to be killed that very night, you were trying to save me from suspicion, not knowing that I, too, planned to break into his offices at the same time as Mary."

"Very good, Sherlock. Follow it through and, indirectly, I got you shot." His tone was bitter, self-recriminating.

"I did rather wonder at your lack of effort into locating the perpetrator during the week I was laid up in hospital."

"Hm," Mycroft pursed his lips and glanced down at where his hands lay folded on the table. "Any further deductions with which you'd like to marvel me?"

"You'd been looking for an excuse to go after Magnussen ever since he printed the Richard Brook story. You knew he'd try to use me to get to you, once news of my return and the deception spread. The Brook-Moriarty fiasco made his paper look quite the fool."

Mycroft's brows rose in mild surprise. "Hm. Yes."

"It's a bit touching, that. In its own way."

His brother scowled, then reached for a packet of cigarettes and his lighter. The two smoked quietly for a minute, utterly ignoring the signs prohibiting them from doing so. "You do realize," Mycroft exhaled, "that there's little I can do for you. You shot a man in cold blood and you did it in front of a dozen witnesses."

Sherlock finished his cigarette and leaned back, eyes closed once more, thinking. "The east wind takes us all in the end. Plucking up the unworthy from the earth…"

"You aren't unworthy, Sherlock. You never were."

A soft huff escaped him but he remained otherwise silent. After a few minutes and another cigarette apiece, Mycroft collected the lighter and his umbrella and made for the door. "I'll be back when I can."

"Happy New Year, Mycroft."

X-X

**A/N: **Thanks for reading!


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